Intelligent cooling fan device and fan rotation speed controlling method thereof

ABSTRACT

A fan cooling device and a method of controlling a fan rotation speed are provided. The fan cooling device includes a thermo sensor, a thermo monitor unit, a processing unit, a driving unit, and a fan. The thermo monitor unit compares the sensed result from the thermo sensor with at least one threshold, and decides whether or not to send an interrupt event according to the compared result. The processing unit executes an interrupt service according to the interrupt event, and then sets and outputs a value of the fan rotation speed. The driving unit drives the fan and controls the rotation speed of the fan according to the value of the fan rotation speed. The fan sends out a wind flow to reduce the internal temperature of a computer system or a CPU.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 96147648, filed on Dec. 13, 2007. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a temperature control deviceand a method thereof, and more particularly, to a cooling fan device anda method of controlling a fan rotation speed.

2. Description of Related Art

With the rapid development of technology, computer hardware has beendeveloped rapidly in recent years, for example, central processing units(CPUs) commonly used by hardware devices such as desktop computers,laptop computers, and even servers and workstations. The clock speed ofthe CPUs becomes increasingly high, so as to cater to the mass'srequirements on processing an increasingly large amount of data andreducing the processing time. With the increase of the clock speed ofthe CPUs, the surface temperature of the CPUs also correspondinglyrises. If no cooling device is installed, the system crash may occur, oreven the hardware devices may be damaged. Therefore, fans must beinstalled to control the surface temperature of the CPUs within a saferange. However, when designing the rotation speed of the fan, themanufacturer often designs taking very extreme use environments intoconsideration, so as to ensure that the surface temperature of the CPUis well controlled to enable the device to operate normally in the saferange under all operating environments. However, in actual usage, theextreme environments set by the manufacturer seldom encounters. In thiscase, the fan rotating at a very high speed does no good to the CPU, butgenerates noise, which may adversely affect the hardware device andcauses problems to the user. Moreover, this design consumes muchelectric power, so the performance of the fan in cooling the CPU israther poor.

In view of the above, in the early days, some manufacturers haveproposed a method of using BIOS to control the fan rotation speed.However, as the BIOS controls the fan rotation speed through a segmentedvariable speed controlling mode, when the program is converted, therising temperature of the CPU generates even more noise due to thehigher acceleration of the fan. Therefore, this design still has its owndisadvantages. Currently, the most widely applied method ofautomatically controlling the fan rotation speed is as shown in FIG. 1,in which the environment temperature is detected in a polling modethrough a software program, so as to adjust the fan rotation speed, suchthat the system maintains at a stable environment temperature. When thetemperature is lower than a preset minimum temperature T_(MIN), the fanoperates at a minimum output power P_(MIN); when the temperature ishigher than a preset maximum temperature T_(MAX), the fan operates at amaximum output power P_(MAX); when the temperature falls between T_(MIN)and T_(MAX), theoretically, the output power under which the fanoperates is changed linearly, i.e., the output power and rotation speedof the fan are automatically changed with the temperature. However, theactual test result shows that, when the temperature falls betweenT_(MIN) and T_(MAX), the output power under which the fan operates doesnot change linearly. At this time, complicated mathematical formulasmust be designed to calculate the corresponding relationship betweeneach temperature within the temperature range and the output power ofthe fan. Thus, circuit elements and software for performing themathematical operations must be additionally installed, so the designcost and element cost are increased accordingly. Moreover, the manner ofadjusting the fan rotating speed through using the software program todetect the temperature in a polling mode through the BIOS has a ratherpoor performance, and consumes excessive large power.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a fan cooling device,which does not require additional circuit elements and software forperforming complicated mathematical operations, and has lower designcost and element cost.

The present invention is also directed to a method of controlling a fanrotation speed, which does not use software programs to detecttemperature in a polling mode through BIOS. Thus, the performance of thefan can be effectively increased, and the power consumption iseffectively reduced.

As embodied and broadly described herein, the present invention providesa fan cooling device, which includes a thermo sensor, a fan, a thermomonitor unit, a processing unit, and a driving unit. The thermo sensorsenses an operating temperature and outputs a sensed result. The fanprovides a wind flow to reduce the operating temperature. The thermomonitor unit is coupled to the thermo sensor for comparing the sensedresult with at least one threshold, and deciding whether or not to sendan interrupt event according to the compared result. The processing unitis coupled to the thermo monitor unit for executing an interrupt serviceaccording to the interrupt event, so as to set and output a value of thefan rotation speed. The driving unit is coupled between the processingunit and the fan for driving the fan and controlling the rotation speedof the fan according to the value of the fan rotation speed.

The present invention also provides a method of controlling a fanrotation speed, which includes the following steps. First, an operatingtemperature is sensed to obtain a sensed result. Next, the sensed resultis compared with at least one threshold to obtain a compared result.Next, whether or not to send an interrupt event is decided according tothe compared result. Next, an interrupt service is executed according tothe interrupt event so as to set a value of the fan rotating speed.Next, the fan driven and the rotation speed of the fan are controlledaccording to the value of the fan rotation speed so as to provide a windflow to reduce the operating temperature.

In an embodiment of the present invention, the thermo monitor unit has aplurality of thresholds for defining a plurality of temperature controlranges, such that the fan is controlled to operate at different rotationspeeds under different temperatures.

In an embodiment of the present invention, the method of controlling afan rotation speed further includes providing a rotation speed table.Once the interrupt event occurs, the interrupt service looks up therotation speed table according to the sensed result, so as to obtain acorresponding value of the fan rotation speed.

To sum up, the present invention can achieve the above function simplyby using the interrupt event, and the interrupt service of BIOS ordriver, and through looking up the table. Thus, not only the programarchitecture required by the software is greatly simplified, but alsothe performance of the fan is also effectively improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a power-temperature curve diagram of a conventional method ofautomatically controlling a fan rotation method.

FIG. 2 is a structural view of a fan cooling device according to anembodiment of the present invention.

FIG. 3A is a flow chart of controlling a fan rotation speed according toan embodiment of the present invention.

FIG. 3B is a detailed flow chart of controlling a fan rotation speedaccording to an embodiment of the present invention.

FIG. 4 is a flow chart of Step S36′ as another implementing manner of aninterrupt service (Step S36) shown in FIG. 3B according to an embodimentof the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

In the design of the current computer systems (e.g., personal computers,servers, and workstations), the thermo monitor function is considered asan important factor, in which the thermo monitor motion for the systemand CPU plays an important role, and another important relevant functionlies in the control of the fan rotation speed. The temperature of theCPU changes as the operating system is operated, so the rotation speedof the fan must be adjusted by the system. Embodiments of the presentinvention are described below, in which the intelligent cooling fandevice and the method of controlling a fan rotation speed are used tomaintain the system at a stable environment temperature.

FIG. 2 is a structural view of a fan cooling device according to anembodiment of the present invention. The fan cooling device includes athermo sensor 21, a thermo monitor unit 22, a processing unit 23, adriving unit 24, and a fan 25. The thermo monitor unit 22 is coupled tothe thermo sensor 21. The processing unit 23 is coupled to the thermomonitor unit 22. The driving unit 24 is coupled between the processingunit 23 and the fan 25.

Hereinafter, the operation modes of the elements in this embodiment aredescribed below with reference to FIGS. 2 and 3A. In Step S33, thethermo sensor 21 senses the operating temperature within the computersystem or the operating temperature of devices such as CPU, and outputsthe sensed result to the thermo monitor unit 22. In Step S34, the thermomonitor unit 22 compares the sensed result of the thermo sensor 21 withat least one threshold. In Step S35, the thermo monitor unit 22 decideswhether to send an interrupt event to the processing unit 23 or notaccording to the compared result. If the sensed result reaches thethreshold, the process continues to perform Step S36. If the sensedresult is lower than the threshold, the process enters into Step S37 tomaintain the original value of the fan rotation speed. Next, in StepS38, the driving unit 24 drives the fan 25 and controls the rotationspeed of the fan 25 according to the original fan rotation speed.

In Step S36, if the processing unit 23 receives the interrupt event sentfrom the thermo monitor unit 22, the processing unit 23 executes aninterrupt service according to the interrupt event, so as to set andoutput the value of the fan rotation speed to the driving unit 24.Detailed steps of the interrupt service will be described later. In StepS38, the driving unit 24 drives the fan 25 and controls the rotationspeed of the fan 25 according to the value of the fan rotation speedprovided by the processing unit 23. Upon receiving the value of the fanrotation speed sent from the driving unit 24, the fan 25 provides thewind flow to reduce the operating temperature. Finally, the processreturns to Step S33 again.

Generally, before entering the operating system, the computer system isbooted and loaded with some software programs required by the system. InFIG. 3B, the process of FIG. 3A is resumed, and the power on self test(POST) steps S31-S32 are further illustrated, as well as the detailedsub-steps S36 a-S36 c of the interrupt service step S36. Referring toFIGS. 2 and 3B, the POST procedure includes two steps: setting a fanrotation speed table S31 and initializing the interrupt service S32. InStep S31, the rules for the fan rotation speed must be defined, whichare relevant to the temperature, that is, the rotation speed table iscreated according to the relationship between the fan rotation speed andthe temperature. First, one or more thresholds are defined in therotation speed table, e.g., 27° C., 31° C., and 35° C. (the temperaturesmay also be set by the user). According to the operating temperaturesensed by the thermo sensor 21, the rotation speed table may be set asfollows: if the operating temperature is equal to or higher than 35° C.,the fan 25 is set to rotate at a full speed; if the operatingtemperature is lower than 35° C. but equal to or higher than 31° C., thefan 25 is set to rotate at a mid speed (90% of the full speed); if theoperating temperature is lower than 31° C. but equal to or higher than27° C., the fan 25 is set to rotate at a low speed (70% of the fullspeed); and if the operating temperature is lower than 27° C., the fan25 is set to rotate at a lowest speed (60% of the full speed). Next, inStep S32, the interrupt service is initialized such that the processingunit 23 can execute the interrupt service, once the interrupt event isreceived.

Similarly, referring to FIGS. 2 and 3B, after setting the fan rotationspeed table and initializing the interrupt service, the computer systemloads the operating system. In most of the working duration, theoperating system need not process operations relevant to temperaturecontrol so the overall performance of the system is improved. The thermomonitor motion is taken over by the thermo sensor 21 and the thermomonitor unit 22. The thermo sensor 21 performs Steps S33 to sense theoperating temperature, and outputs the sensed result to the thermomonitor unit 22. The thermo monitor unit 22 performs Step S34 to comparethe sensed result with the threshold, and then performs Step S35 todecide whether or not to send the interrupt event to the processing unit23. For example, if the sensed result of the thermo sensor 21 shows thatthe current operating temperature is approximately equal to thethreshold (e.g., 27° C., 31° C., or 35° C.), the system may need toadjust the fan rotation speed according to the rotation speed table.Therefore, the thermo monitor unit 22 sends the interrupt event to theprocessing unit 23. The operation modes of Steps S33-S35 have alreadybeen described above, and therefore will not be repeated again.

The detailed sub-steps of the interrupt service (Step S36) are furtherillustrated, which include the following three specific sub-steps:reading the sensed result (step S36 a), determining the value of the fanrotation speed according to the fan rotation speed table (step S36 b),and outputting the speed of the fan rotation speed (step S36 c). In StepS36 a, the processing unit 23 reads the current operating temperature(i.e., the sensed result of the thermo sensor 21). In this embodiment,the thermo monitor unit 22 monitors the sensed result of the thermosensor 21 at any time, so the processing unit 23 can obtain the currentoperating temperature (the sensed result) from the thermo monitor unit22. In other embodiments, the processing unit 23 may obtain the currentoperating temperature (the sensed result) directly from the thermosensor 21.

In Step S36 b, the processing unit 23 determines the value of the fanrotation speed by means of looking up the rotation speed table preset inStep S31. For example, after receiving the interrupt event sent from thethermo monitor unit 22, the processing unit 23 reads the currentoperating temperature from the thermo monitor unit 22 (or the thermosensor 21), and then looks up the above rotation speed table. Accordingto the sensed result of the thermo sensor 21, the processing unit 23 canfind out the corresponding value of the fan rotation speed from therotation speed table. Similarly, if the operating temperature is equalto or higher than 35° C., the corresponding value of the fan rotationspeed is 100% (full speed); if the operating temperature falls between35° C. and 31° C., the corresponding value of the fan rotation speed is90% (mid speed); if the operating temperature falls between 31° C. and27° C., the corresponding value of the fan rotation speed is 70% (lowspeed); and if the operating temperature is lower than 27° C., thecorresponding value of the fan rotation speed is 60% (lowest speed).

Next, in Step S36 c, the processing unit 23 outputs the value of the fanrotation speed obtained by looking up the table to the driving unit 24.Finally, in Step S38, the driving unit 24 drives the fan 25 and controlsthe rotation speed of the fan 25 according to the value of the fanrotation speed. Once the interrupt service in Step S36 is completed, theprocessing unit 23 need not process operations relevant to temperaturecontrol any more (until the thermo monitor unit 22 sends anotherinterrupt event), so the overall performance of the system is improved.

In another embodiment of the present invention, the interrupt servicemay be implemented in another mode. FIG. 4 is a flow chart of Step S36′as another implementing manner of an interrupt service (Step S36) shownin FIG. 3B according to an embodiment of the present invention.Referring to FIGS. 2 and 4, the processing unit 23 similarly reads theoperating temperature obtained from the thermo sensor 21 or the thermomonitor unit 22, in Step S36 a. Next, in Step S36 d, the value of thefan rotation speed is obtained by means of looking up the fan rotationspeed table, and then the value of the fan rotation speed obtained fromthe fan rotation speed table is compared with the current value of thefan rotation speed. If the two values are the same (which indicates thatthe current value of the fan rotation speed does not need to bechanged). In Step S38, the driving unit 24 drives the fan 25 andcontrols the rotation speed of the fan 25 according to the original fanrotation speed. If the two values are different (which indicates thatthe current value of the fan rotation speed needs to be changed), theprocessing unit 23 sets the value of the fan rotation speed obtainedfrom the fan rotation table as the “current value of the fan rotationspeed”, in Step S36 e, and then outputs the value of the fan rotationspeed, in Step S36 c. Next, the driving unit 24 drives the fan 25 andcontrols the rotation speed of the fan 25 according to the newly-set fanrotation speed, in Step S38. Thus, the fan 25 rotates at the newrotation speed to send the wind flow, so as to reduce the temperature ofthe interior of the computer system or the CPU.

In the embodiments of the present invention, the principle for changingthe rotation speed of the fan lies in the voltage output function, whichis achieved, for example, through the pulse width modulation (PWM) mode.The so-called PWM mode converts the output voltage to be supplied in apulse mode, and changes the width and number of the pulses to obtain therequired voltage and frequency. This function changes the voltage outputsettings relevant to the fan rotation speed, such that the PWM functionof the hardware can provide different voltages to the fan, and thus, therotation speed is changed, and heat dissipation is effectively achieved.

As for elements mentioned in the embodiments of the present invention,the thermo sensor 21, the thermo monitor unit 22, and the driving unit24 may be manufactured into a single thermo chip, or the thermo sensor21, the thermo monitor unit 22, and the driving unit 24 may beintegrated into the processing unit 23, so as to reduce the cost andsave the space required by circuit wiring.

To sum up, in the embodiments of the present invention, the abovefunctions are achieved simply by using the interrupt event and theinterrupt service of the BIOS or driver, and thus, not only the programarchitecture required by the software is greatly simplified, but theperformance of the fan is also effectively improved. Moreover, besidesbeing applied in computer devices such as personal computers, servers,and workstations, or CPUs, the cooling fan device of the presentinvention may also be applied on any element requiring heat dissipationwithin the products such as home appliances.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A fan cooling device, comprising: a thermo sensor, for sensing anoperating temperature and outputting a sensed result; a fan, forproviding a wind flow to reduce the operating temperature; a thermomonitor unit, coupled to the thermo sensor, for comparing the sensedresult with at least one threshold, and deciding whether or not to sendan interrupt event according to a compared result; a processing unit,coupled to the thermo monitor unit, for executing an interrupt serviceaccording to the interrupt event to set and output a value of a fanrotation speed; and a driving unit, coupled between the processing unitand the fan, for driving the fan and controlling a rotation speed of thefan according to the value of the fan rotation speed.
 2. The fan coolingdevice according to claim 1, wherein the thermo monitor unit comprises aplurality of thresholds for defining a plurality of temperature controlranges.
 3. The fan cooling device according to claim 1, wherein theinterrupt service comprises a rotation speed table, and wherein once theinterrupt event occurs, the interrupt service reads the sensed resultfrom the thermo sensor, looks up the rotation speed table to obtain acorresponding value of the fan rotation speed, and outputs the value ofthe fan rotation speed to the driving unit.
 4. The fan cooling deviceaccording to claim 1, wherein the operating temperature is an internaltemperature of a computer system.
 5. The fan cooling device according toclaim 4, wherein the operating temperature is a temperature of a centralprocessing unit (CPU).
 6. A method of controlling a fan rotation speed,comprising: sensing an operating temperature to obtain a sensed result;comparing the sensed result with at least one threshold to obtain acompared result; deciding whether or not to send an interrupt eventaccording to a compared result; executing an interrupt service accordingto the interrupt event to set a value of a fan rotation speed; anddriving a fan and controlling a rotation speed of the fan according tothe value of the fan rotation speed to provide a wind flow to reduce theoperating temperature.
 7. The method of controlling a fan rotation speedaccording to claim 6, further comprising: setting a plurality ofthresholds to define a plurality of temperature control ranges, whereinwhen the sensed result indicates that the operating temperature fallswithin one of the temperature control ranges, the interrupt service setsa corresponding value of the fan rotation speed.
 8. The method ofcontrolling a fan rotation speed according to claim 6, furthercomprising providing a rotation speed table, wherein once the interruptevent occurs, the interrupt service looks up the rotation speed tableaccording to the sensed result, so as to obtain the corresponding valueof the fan rotation speed.
 9. The method of controlling a fan rotationspeed according to claim 6, wherein the operating temperature is aninternal temperature of a computer system.
 10. The method of controllinga fan rotation speed according to claim 9, wherein the operatingtemperature is a temperature of a CPU.